1. Technical Field
The present invention relates to digital cellular radio networks such as Global System for Mobile communication (GSM) networks, and more particularly, relates to solutions for providing seamless mobility between a GSM network and a different local radio network (e.g., wireless LAN), particularly when such local radio network is used in hotspot areas or an area where high bit rate or high quality of service (QoS) is desirable without having different terminals, devices and numbers.
2. Related Art
GSM networks represent digital cellular networks and personal communications systems which allow one network channel to support multiple conversations using time division multiple access (TDMA) technology. In those GSM networks, TDMA takes one network channel and divides it up into slices of time. The mobile phone user is given one of these slices of time for a brief pre-scheduled interval. The interval is so short that neither the mobile user nor other mobile users on the same radio channel notice that they are transmitting or receiving on a fraction of the channel. In this manner, the capacity of the network is significantly increased over standard analog cellular, which requires an entire channel for transmission.
GSM networks may be used on several different radio bands (also known as the frequency of the network), for example, standard 900 MHz (used mostly in original European GSM networks), 1800 MHz (used mostly in Personal Communications Networks/Digital Communication Systems PCN/DCS in the United Kingdom) and 1900 MHz (used mostly in Personal Communications System PCS in North America). GSM technical standards are provided by the European Telecommunications Standards Institute (ETSI) and can be obtained directly from ETSI via the web site: www.ETSI.fr.
Each GSM network is comprised of several major portions: a mobile phone, subscriber information, a radio network, a switching system and network intelligence (primarily databases). The mobile phone is called a mobile station which contains therein an electronic card, known as a subscriber identity module (SIM) to identify the user. Mobile stations communicate with nearby radio towers called base stations. Base stations convert the radio signal for communication to a switching system. The switching system connects calls to other mobile stations or routes the call to the public switched telephone network (PSTN) or other type of networks such as the public packet data network (PPDN) and the Internet. The switching system is connected to several databases that contain customer information to check authorization for services (e.g., voice, messaging, data and image services) and process call features.
Many GSM networks support the use of multi-mode, multi-frequency or multi-technology mobile stations that are capable of performing many advanced services. GSM mobile stations may combine many advanced services offered by GSM technology with the latest in computers, displays and other technologies. For example, multi-frequency GSM phones may allow a single handset to operate (roam) on GSM systems that have different frequencies, for example standard GSM (900 MHz), DCS (1800 MHz) or US PCS (1900 MHz). Multi-mode GSM phones may allow the same handset to access different radio technologies including Digital European Cordless Telephones (DECT). Multi-technology GSM phones may allow the handset to access and display different information sources (e.g., Internet web browsing).
However, there is still no seamless mobility between GSM networks and different radio networks such as, for example, wireless local area networks (WLAN), Bluetooth networks or 3G WCDMA radio networks. There is no way where a mobile station can roam from a GSM network to another radio network automatically and handover from and to another radio network to the GSM network successfully. In addition, there is no system where the same GSM mobile station can select to use another high capacity radio seamlessly in either an IDLE or ACTIVE mode while remaining accessible to other types of mobile stations, terminals or devices without any user actions.
Accordingly, there is a need for providing seamless mobility between a GSM network and a different local radio network, particularly when the local radio network is used in hotspot areas or an area where higher bit rate or high quality of service (QoS) is desirable without having different terminals, devices and numbers.